The Cd-tolerant and sodium alginate(SA)-synthesizing Pseudomonas putida XMS-1was characterized for Cd immobilization in solution.Additionally,the XMS-1 mutant constructed by deleting SA-synthesizing regulatory gene al...The Cd-tolerant and sodium alginate(SA)-synthesizing Pseudomonas putida XMS-1was characterized for Cd immobilization in solution.Additionally,the XMS-1 mutant constructed by deleting SA-synthesizing regulatory gene algB(△algB)were characterized for their roles in Cd uptake in Chinese chive in the Cd-contaminated soil.Between 12 and 48 h of incubation,the XMS-1△algBmutant significantly reduced solution Cd concentrations by 81%compared with the control but increased the Cd concentrations by 36%compared with XMS-1.After 48 h of incubation,the XMS-1△algB mutant significantly increased the Cd concentration by 36%and decreased the expolysaccharide(EPS)and SA concentrations by 30%-32%and cell surface-adsorbed Cd content by 24%in the Cd-containing medium,compared with XMS-1.The XMS-1△algB mutant significantly increased the root and leaf Cd contents of Chinese chive by 15%-50%and exchangeable Cd content by 17%and decreased the Fe-Mn oxideand organic matter-bound Cd contents by 17%-23%,compared with XMS-1.Furthermore,the XMS-1△algBmutant significantly decreased the EPS content by 33%,copies of algD gene involved in EPS production by 7.7-fold,and the interactions between the amino,hydroxyl,and carbonyl groups and Cd in the Cd-contaminated soil,compared with XMS-1.These results suggested that algB promoted XMS-1-mediated Cd-stabilizing related gene abundance and interactions between soil and Cd and decreased Cd uptake in Chinese chive.These findings may provide an effective and eco-friendly way using SA-producing bacteria for safe production of vegetables in the Cd-polluted soil.展开更多
A bacterial strain that utilized o-chloronitrobenzene （o-CNB） as the sole carbon, nitrogen and energy sources was isolated from an activated sludge collected from an industrial waste treatment plant. It was identifi...A bacterial strain that utilized o-chloronitrobenzene （o-CNB） as the sole carbon, nitrogen and energy sources was isolated from an activated sludge collected from an industrial waste treatment plant. It was identified as Pseudomonas putida based on its morphology, physiological, and biochemical characteristics with an automatic biometrical system and the 16S rRNA sequence analysis. Microcosm study showed that the biodegradation of o-CNB was optimized at culture medium pH 8.0 and 32℃. At these conditions, the strain degraded 85% of o-CNB at a starting concentration of 1.1 mmol/L in 42 h. o-Chloroaniline was identified as the major metabolite with high performance liquid chromatography （HPLC） and gas chromatography-mass spectrometry （GC-MS）. The study showed that o-CNB degradation by Pseudomonas putida OCNB-1 was initiated by aniline dioxyenase, nitrobenzene reductase and catechol-l,2- dioxygenase.展开更多
The enhanced biological phosphorus removal （EBPR） method is widely adopted for phosphorus removal from wastewater, yet little is known about its microbiological and molecular mechanisms. Therefore, it is difficult t...The enhanced biological phosphorus removal （EBPR） method is widely adopted for phosphorus removal from wastewater, yet little is known about its microbiological and molecular mechanisms. Therefore, it is difficult to predict and control the deterioration of the EBPR process in a large-scale municipal sewage treatment plant. This study used a novel strain isolated in the laboratory, Pseudomonas putida GM6, which had a high phosphate accumulating ability and could recover rapidly from the deteriorated system and enhance the capability of phosphorus removal in activated sludge. Strain GM6 marked with gfp gene, which was called GMTR, was delivered into a bench-scale sequencing batch reactor （SBR） of low efficiency, to investigate the colonization of GMTR and removal of phosphorus. After 21 days, the proportion of GMTR in the total bacteria of the sludge reached 9.2%, whereas the phosphorus removal rate was 96%, with an effluent concentration of about 0.2 mg L^-1. In the reactor with the addition of GMTR, phosphorus was removed quickly, in 1 h under anaerobic conditions, and in 2 h under aerobic conditions. These evidences were characteristic of EBPR processes. Field testing was conducted at a hospital sewage treatment facility with low phosphorus removal capability. Twentyone days after Pseudomonas putida GM6 was added, effluent phosphorus concentration remained around 0.3 mg L^-1, corresponding to a removal rate of 96.8%. It was therefore demonstrated that Pseudomonas putida GM6 could be used for a quick startup and enhancement of wastewater biological phosphorus removal, which provided a scientific basis for potential large-scale engineering application.展开更多
The majority of nanoparticles tend to agglomerate in bacterial growth media. Thus, nanoparticle-specific characteristics can get lost. To investigate the influence of nanoparticles on bacteria, these particles should ...The majority of nanoparticles tend to agglomerate in bacterial growth media. Thus, nanoparticle-specific characteristics can get lost. To investigate the influence of nanoparticles on bacteria, these particles should remain in their nanoparticulate state. The present study demonstrates the stabilization of commercially available zinc oxide (ZnO) with sodiumhexametaphosphate (SHMP) in bacterial growth medium (LB) to avoid agglomeration of these particles after the addition to LB. This established method is appropriate to stabilize ZnO agglomerates as small as 43 nm. The method of fractionated centrifugation was used to obtain stable agglomerates (also stable in the presence of bacteria) with different mean diameters. The SHMP-stabilized ZnO inhibits the growth of Pseudomonas putida with increasing concentration (up to 500 mg/L) and decreasing agglomerate size (43 - 450 nm).展开更多
基金supported by the National Natural Science Foundation of China(No.41977199).
文摘The Cd-tolerant and sodium alginate(SA)-synthesizing Pseudomonas putida XMS-1was characterized for Cd immobilization in solution.Additionally,the XMS-1 mutant constructed by deleting SA-synthesizing regulatory gene algB(△algB)were characterized for their roles in Cd uptake in Chinese chive in the Cd-contaminated soil.Between 12 and 48 h of incubation,the XMS-1△algBmutant significantly reduced solution Cd concentrations by 81%compared with the control but increased the Cd concentrations by 36%compared with XMS-1.After 48 h of incubation,the XMS-1△algB mutant significantly increased the Cd concentration by 36%and decreased the expolysaccharide(EPS)and SA concentrations by 30%-32%and cell surface-adsorbed Cd content by 24%in the Cd-containing medium,compared with XMS-1.The XMS-1△algB mutant significantly increased the root and leaf Cd contents of Chinese chive by 15%-50%and exchangeable Cd content by 17%and decreased the Fe-Mn oxideand organic matter-bound Cd contents by 17%-23%,compared with XMS-1.Furthermore,the XMS-1△algBmutant significantly decreased the EPS content by 33%,copies of algD gene involved in EPS production by 7.7-fold,and the interactions between the amino,hydroxyl,and carbonyl groups and Cd in the Cd-contaminated soil,compared with XMS-1.These results suggested that algB promoted XMS-1-mediated Cd-stabilizing related gene abundance and interactions between soil and Cd and decreased Cd uptake in Chinese chive.These findings may provide an effective and eco-friendly way using SA-producing bacteria for safe production of vegetables in the Cd-polluted soil.
基金National Natural Science Foundation of China(No.21206055)National High Technology Research and Development Program of China(863 Program)(No.2011AA02A211)~~
基金supported by the National Natural Sci- ence Foundation of China (No. 50278036)the National Hi-Tech Research and Development Program (863) of China (No. 2006AA06Z378)
文摘A bacterial strain that utilized o-chloronitrobenzene （o-CNB） as the sole carbon, nitrogen and energy sources was isolated from an activated sludge collected from an industrial waste treatment plant. It was identified as Pseudomonas putida based on its morphology, physiological, and biochemical characteristics with an automatic biometrical system and the 16S rRNA sequence analysis. Microcosm study showed that the biodegradation of o-CNB was optimized at culture medium pH 8.0 and 32℃. At these conditions, the strain degraded 85% of o-CNB at a starting concentration of 1.1 mmol/L in 42 h. o-Chloroaniline was identified as the major metabolite with high performance liquid chromatography （HPLC） and gas chromatography-mass spectrometry （GC-MS）. The study showed that o-CNB degradation by Pseudomonas putida OCNB-1 was initiated by aniline dioxyenase, nitrobenzene reductase and catechol-l,2- dioxygenase.
基金Project supported by the National Natural Science Foundation of China (Nos.30500010 and 50308011).
文摘The enhanced biological phosphorus removal （EBPR） method is widely adopted for phosphorus removal from wastewater, yet little is known about its microbiological and molecular mechanisms. Therefore, it is difficult to predict and control the deterioration of the EBPR process in a large-scale municipal sewage treatment plant. This study used a novel strain isolated in the laboratory, Pseudomonas putida GM6, which had a high phosphate accumulating ability and could recover rapidly from the deteriorated system and enhance the capability of phosphorus removal in activated sludge. Strain GM6 marked with gfp gene, which was called GMTR, was delivered into a bench-scale sequencing batch reactor （SBR） of low efficiency, to investigate the colonization of GMTR and removal of phosphorus. After 21 days, the proportion of GMTR in the total bacteria of the sludge reached 9.2%, whereas the phosphorus removal rate was 96%, with an effluent concentration of about 0.2 mg L^-1. In the reactor with the addition of GMTR, phosphorus was removed quickly, in 1 h under anaerobic conditions, and in 2 h under aerobic conditions. These evidences were characteristic of EBPR processes. Field testing was conducted at a hospital sewage treatment facility with low phosphorus removal capability. Twentyone days after Pseudomonas putida GM6 was added, effluent phosphorus concentration remained around 0.3 mg L^-1, corresponding to a removal rate of 96.8%. It was therefore demonstrated that Pseudomonas putida GM6 could be used for a quick startup and enhancement of wastewater biological phosphorus removal, which provided a scientific basis for potential large-scale engineering application.
文摘The majority of nanoparticles tend to agglomerate in bacterial growth media. Thus, nanoparticle-specific characteristics can get lost. To investigate the influence of nanoparticles on bacteria, these particles should remain in their nanoparticulate state. The present study demonstrates the stabilization of commercially available zinc oxide (ZnO) with sodiumhexametaphosphate (SHMP) in bacterial growth medium (LB) to avoid agglomeration of these particles after the addition to LB. This established method is appropriate to stabilize ZnO agglomerates as small as 43 nm. The method of fractionated centrifugation was used to obtain stable agglomerates (also stable in the presence of bacteria) with different mean diameters. The SHMP-stabilized ZnO inhibits the growth of Pseudomonas putida with increasing concentration (up to 500 mg/L) and decreasing agglomerate size (43 - 450 nm).
